Prevention of premature myocardial infarction is an important public health issue. Two different approaches may be used in order to prevent premature myocardial infarction, a high-risk strategy and a population strategy. The report discusses prevention of myocardial infarction in middle-aged Norwegian individuals by reducing total serum cholesterol and using the high risk and population strategies. A combination of these strategies is recommended, but with major emphasis on the population approach. Both trials and calculations indicate that the high-risk strategy should be limited to subjects with very high serum cholesterol (e.g. greater than or equal to 8 mmol/l in middle-aged men).